Tens of thousands of supporters of a powerful Iraqi Shiite cleric have rallied in central Baghdad to press demands for reform and an end to alleged corruption in the government.

Friday's rally was held under tight security following a devastating Islamic State group attack that killed nearly 300 in Baghdad on July 3.

Earlier this year, supporters of Muqtada al-Sadr stormed the Green Zone, a sprawling complex housing the prime minister's office, parliament and Western embassies.

The protesters waved Iraqis flag and chanted slogans as patriotic music blared from loudspeakers.

Al-Sadr's speech was cut short after the crowd surged forward, threatening a potentially deadly stampede. The cleric then quickly left. Several men were injured as they surged forward or jumped off a ramp to get closer to al-Sadr.